Run tests in parallel, dont use working dir

This changes the CloudPrepper to not store intermediate artifacts in
the current directory, allowing the tests to be ran in parallel.

Author: r2d4

tests/integration_test.go

@@ -162,6 +162,7 @@ func TestDiffAndAnalysis(t *testing.T) {
 	}
 	for _, test := range tests {
 		t.Run(test.description, func(t *testing.T) {
+			t.Parallel()
 			args := []string{test.subcommand, test.imageA}
 			if test.imageB != "" {
 				args = append(args, test.imageB)

utils/image_prep_utils.go

@@ -128,7 +128,13 @@ func (p CloudPrepper) getFileSystem() (string, error) {
 	URLPattern := regexp.MustCompile("^.+/(.+(:.+){0,1})$")
 	URLMatch := URLPattern.FindStringSubmatch(p.Source)
 	// Removing the ":" so that the image path name can be <image><tag>
-	path := strings.Replace(URLMatch[1], ":", "", -1)
+	sanitizedName := strings.Replace(URLMatch[1], ":", "", -1)
+
+	path, err := ioutil.TempDir("", sanitizedName)
+	if err != nil {
+		return "", err
+	}
+
 	ref, err := docker.ParseReference("//" + p.Source)
 	if err != nil {
 		return "", err
@@ -156,10 +162,6 @@ func (p CloudPrepper) getFileSystem() (string, error) {
 		return "", err
 	}
 
-	if _, ok := os.Stat(path); ok != nil {
-		os.MkdirAll(path, 0777)
-	}
-
 	for _, b := range img.LayerInfos() {
 		bi, _, err := imgSrc.GetBlob(b)
 		if err != nil {